org.apache.log4j.db

Class DBAppender

java.lang.Object

org.apache.log4j.AppenderSkeleton

org.apache.log4j.db.DBAppender

All Implemented Interfaces:

org.apache.log4j.Appender, org.apache.log4j.spi.OptionHandler, org.apache.log4j.xml.UnrecognizedElementHandler

public class DBAppender
extends org.apache.log4j.AppenderSkeleton
implements org.apache.log4j.xml.UnrecognizedElementHandler

The DBAppender inserts loggin events into three database tables in a format independent of the Java programming language. The three tables that DBAppender inserts to must exists before DBAppender can be used. These tables may be created with the help of SQL scripts found in the src/java/org/apache/log4j/db/dialect directory. There is a specific script for each of the most popular database systems. If the script for your particular type of database system is missing, it should be quite easy to write one, taking example on the already existing scripts. If you send them to us, we will gladly include missing scripts in future releases.

If the JDBC driver you are using supports the Statement.getGeneratedKeys()method introduced in JDBC 3.0 specification, then you are all set. Otherwise, there must be an SQLDialectappropriate for your database system. Currently, we have dialects for PostgreSQL, MySQL, Oracle and MsSQL. As mentioed previously, an SQLDialect is required only if the JDBC driver for your database system does not support the getGeneratedKeys method.

supported dialects

RDBMS	supports getGeneratedKeys() method	specific SQLDialect support
PostgreSQL	NO	present and used
MySQL	YES	present, but not actually needed or used
Oracle	YES	present, but not actually needed or used
DB2	YES	not present, and not needed or used
MsSQL	YES	not present, and not needed or used
HSQL	NO	present and used

Performance: Experiments show that writing a single event into the database takes approximately 50 milliseconds, on a "standard" PC. If pooled connections are used, this figure drops to under 10 milliseconds. Note that most JDBC drivers already ship with connection pooling support.

Configuration DBAppender can be configured programmatically, or using JoranConfigurator. Example scripts can be found in the tests/input/db directory.

Author:

Ceki Gülcü, Ray DeCampo

Field Summary

Fields inherited from class org.apache.log4j.AppenderSkeleton

closed, errorHandler, headFilter, layout, name, tailFilter, threshold

Constructor Summary

Constructors

Constructor and Description
DBAppender()

Method Summary

Modifier and Type	Method and Description
void	activateOptions()
protected void	append(org.apache.log4j.spi.LoggingEvent event)
void	close()
ConnectionSource	getConnectionSource()
boolean	getLocationInfo() Returns value of the LocationInfo property which determines whether caller's location info is written to the database.
boolean	parseUnrecognizedElement(Element element, Properties props)
boolean	requiresLayout() Gets whether appender requires a layout.
void	setConnectionSource(ConnectionSource connectionSource)
void	setLocationInfo(boolean locationInfo) If true, the information written to the database will include caller's location information.

Methods inherited from class org.apache.log4j.AppenderSkeleton

addFilter, clearFilters, doAppend, finalize, getErrorHandler, getFilter, getFirstFilter, getLayout, getName, getThreshold, isAsSevereAsThreshold, setErrorHandler, setLayout, setName, setThreshold

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DBAppender

public DBAppender()

Method Detail

activateOptions

public void activateOptions()

Specified by:

activateOptions in interface org.apache.log4j.spi.OptionHandler

Overrides:

activateOptions in class org.apache.log4j.AppenderSkeleton

getConnectionSource

public ConnectionSource getConnectionSource()

Returns:

Returns the connectionSource.

setConnectionSource

public void setConnectionSource(ConnectionSource connectionSource)

Parameters:

connectionSource - The connectionSource to set.

append

protected void append(org.apache.log4j.spi.LoggingEvent event)

Specified by:

append in class org.apache.log4j.AppenderSkeleton

close

public void close()

Specified by:

close in interface org.apache.log4j.Appender

getLocationInfo

public boolean getLocationInfo()

Returns value of the LocationInfo property which determines whether caller's location info is written to the database.

setLocationInfo

public void setLocationInfo(boolean locationInfo)

If true, the information written to the database will include caller's location information. Due to performance concerns, by default no location information is written to the database.

requiresLayout

public boolean requiresLayout()

Gets whether appender requires a layout.

Specified by:

requiresLayout in interface org.apache.log4j.Appender

Returns:

false

parseUnrecognizedElement

public boolean parseUnrecognizedElement(Element element,
                                        Properties props)
                                 throws Exception

Specified by:

parseUnrecognizedElement in interface org.apache.log4j.xml.UnrecognizedElementHandler

Throws:

Exception